JP4799294B2 - Method for producing high formability Al-Mg alloy plate - Google Patents

Description

  The present invention relates to a method of manufacturing an aluminum alloy plate for forming used for body parts of automobiles, various other vehicle parts, various electronic / electric equipment parts such as chassis and panels of electronic / electric equipment, etc. The present invention relates to a method for producing a highly formable aluminum alloy plate made of an Al-Mg alloy having excellent formability as well as strength.

  Conventionally, cold rolled steel sheets were often used for automobile body sheets, but recently there has been a growing demand for lighter automobiles to improve fuel economy in order to reduce global warming and reduce energy costs. Therefore, instead of the conventional cold-rolled steel plate, there is an increasing tendency to use an aluminum alloy plate having substantially the same strength as the cold-rolled steel plate and a specific gravity of about 1/3 for the body sheet of an automobile. Recently, aluminum alloy plates are often used for molded parts such as panels and chassis of electronic and electric devices other than automobiles.

  By the way, as an aluminum alloy plate as such a forming material, conventionally, Al-Mg based JIS 5052 alloy or JIS 5182 alloy O material has been most widely used. As a method for producing a forming material made of such an Al—Mg-based aluminum alloy, conventionally, casting is generally performed by a DC casting method and subjected to a homogenization treatment, followed by hot rolling and further cold rolling. And a method of performing recrystallization heat treatment is applied. However, Al-Mg-based aluminum alloy sheets for forming work manufactured by conventional methods are almost the same as cold-rolled steel sheets, but their formability, especially deep drawability, is comparable to that of cold-rolled steel sheets. The fact is that it is inferior.

By the way, in cold-rolled steel sheets, the Rankford value (r value) has been widely used as an index of formability, particularly deep drawability. And the higher the rankford value, especially the average rankford value (average r value), the better the deep drawability. Here, the average r value is an average value of r values (r ₀ , r ₄₅ , r ₉₀ ) measured in directions of 0 °, 45 °, and 90 ° with respect to the rolling direction, and the average r value = ( r ₀ + 2 × r ₄₅ + r ₉₀ ) / 4.

  On the other hand, in general, it is well known that deep drawability is greatly influenced by the texture in a forming material. And in the cold-rolled steel sheet having a body-centered cubic lattice structure, the main orientation plane parallel to the plane of the rolled texture becomes the {111} plane, and the average r value is increased by increasing the orientation density of the {111} plane. It is known that the deep drawability is improved. And in cold-rolled steel sheets, the crystal orientation obtained by cold rolling / recrystallization heat treatment is the {111} plane as described above, so the orientation density of the {111} plane is increased to improve the deep drawability. The method for this is already well established.

  On the other hand, in the case of an aluminum alloy having a face-centered cubic lattice structure, if the heat treatment is performed by a conventional general method, not only the {111} plane effective for improving the formability is formed, but also the formability. The orientation density of the {100} plane that hinders the orientation becomes the main orientation, and the average r value cannot be sufficiently increased, making it difficult to improve the moldability, particularly the deep drawability.

  Therefore, recently, for example, Non-Patent Document 1 proposes a technique for forming a {111} texture by applying shear deformation to an aluminum alloy to improve the average r value and deep drawability. This Non-Patent Document 1 discloses a theoretical analysis that the r value becomes high with a material of {111} texture, and as a specific method for forming {111} texture, hot rolling and Methods have been proposed in which shear deformation is introduced by applying warm rolling in which the rolling is performed at an intermediate temperature of cold rolling or different circumferential speed rolling in which the rotational circumferential speeds of the upper and lower rolling rolls are different during rolling.

  On the other hand, as patent documents, Patent Document 1 applies different peripheral speed rolling, and Patent Document 2 applies warm different peripheral speed rolling, thereby forming a {111} texture and improving deep drawability, respectively. Has been proposed. In addition, the inventors of Patent Document 1 also disclose non-patent documents 2 and 3 as to techniques for applying shear deformation to an aluminum alloy by different speed rolling.

JP 2003-305503 A JP-A-2005-139494 Textbook of the 50th Symposium of the Japan Institute of Light Metals, “Analysis and Control of Recrystallization and Texture” (1996), P18 Light Metal, Vol. 50, No. 7 (2000), P335-340 Light Metal, Vol.52, No.4 (2002), P185-189

  By the way, in the prior art as described above, it has been shown that applying shear deformation by different circumferential speed rolling is effective for texture control in an Al alloy, but there are still problems in actually performing this. There is not enough consideration. That is, for example, the inventors of Patent Document 1 have decided to carry out different peripheral speed rolling for imparting shear deformation to a material in a non-lubricated state in other Non-Patent Documents 2 and 3, as described above. Rolling in a non-lubricated state is effective in terms of the efficiency of introducing shear deformation, but is not suitable for actually producing a press-molding material with excellent surface quality. In other words, with different peripheral speed rolling, the surface of the material is subject to friction with the roll, so surface rolling (surface roughening and cracking) is likely to occur if rolling in an unlubricated state, and in extreme cases, rolling itself becomes impossible. End up. Moreover, in the different peripheral speed rolling in a non-lubricated state, aluminum adhesion tends to occur on the rolling roll, which also makes stable rolling difficult.

  The different speed rolling is not yet established as a general rolling method for aluminum alloys, whereas in the above-mentioned Patent Documents 1 and 2, the surface of an important surface in rolling on an actual mass production scale is used. There is no mention of lubrication, so it must be considered that these prior arts are also supposed to be implemented without lubrication. From that point, the proposals in Patent Documents 1 and 2 are at least industrial. It cannot be said that it has been completed as a technique for obtaining a sound plate material in mass production.

  The present invention has been made against the background described above. The texture control is performed by applying different circumferential speed rolling to improve the r value and deep drawability of the Al-Mg alloy, and at the same time, the surface of the plate. It is intended to solve the problem of obtaining a sound plate material by industrial production on a mass production scale by preventing the occurrence of defects (such as microcracks) and adhesion of the material to a roll.

  The inventors of the present invention use an Al—Mg alloy as a raw material, and by using an appropriate lubricant, perform alternate speed rolling while preventing the occurrence of surface cracks and surface defects to give sufficient shear deformation. As a result of repeated various experiments and examinations to find out the method and conditions, basically, with respect to the Al-Mg alloy material plate, at a temperature in the range of 150 to 300 ° C with a lubricant applied to the surface. When the roll peripheral speed ratio is in the range of 1.2 to 2.5, the roll is subjected to warm different peripheral speed rolling under the condition of a reduction ratio exceeding 85%, and then recrystallized by annealing or solution treatment, so that cracks and The present inventors have found that a highly formable Al—Mg alloy plate having an average r value of 0.9 or more can be obtained while preventing the occurrence of surface defects.

  Specifically, the method for producing a highly formable Al—Mg alloy plate according to the first aspect of the present invention is a range of 150 to 300 ° C. with a lubricant applied to the surface of the Al—Mg alloy material plate. At a temperature within the range, the roll peripheral speed ratio is in the range of 1.2 to 2.5, and the rolling is performed at a different rolling speed at a rolling reduction rate exceeding 85%, and then the recrystallization heat treatment is performed to obtain an average r An Al—Mg alloy plate having a value of 0.9 or more is obtained.

The invention according to claim 2 is the method for producing a highly formable Al—Mg alloy plate according to claim 1, wherein the lubricant has a kinematic viscosity at room temperature of 10 to 350 mm ² / s and a flash point. Using a lubricating oil of 305 ° C. or higher, and attaching the lubricating oil to the Al—Mg alloy material plate so that the amount of the lubricating oil is within the range of 100 to 700 mg / m ² , performing warm different peripheral speed rolling. It is a feature.

  Furthermore, the invention of claim 3 is the method for producing a highly formable Al—Mg alloy plate according to claim 1 or claim 2, wherein the Al—Mg alloy material plate is Mg 2.0 to 6.5%. As the recrystallization heat treatment, the recrystallization heat treatment is performed using an Al—Mg-based alloy plate containing Al and the inevitable impurities in the balance and subjected to warm differential circumferential rolling with a lubricant applied to the surface. It is characterized by annealing at a temperature in the range of ˜570 ° C. and recrystallization.

  The invention of claim 4 is the method for producing a highly formable Al—Mg alloy plate according to claim 1 or claim 2, wherein the Al—Mg alloy material plate is Mg 2.0 to 6.5%. And an Al-Mg alloy plate containing 0.05 to 0.5% of Cu and the balance being Al and unavoidable impurities, and performing a warm different peripheral speed rolling with a lubricant applied to the surface. Then, as said recrystallization heat processing, it anneals at the temperature within the range of 310-570 degreeC, and is recrystallized.

  The invention of claim 5 is the method for producing a highly formable Al—Mg alloy plate according to claim 1 or claim 2, wherein the Al—Mg alloy material plate is Mg 2.0 to 6.5. % And Cu 0.5% and 1.8% or less, with the balance being Al-Mg based alloy plate made of Al and inevitable impurities, with a lubricant applied to its surface, After performing the rapid rolling, as the recrystallization heat treatment, a solution treatment for heating to a temperature of 510 to 570 ° C. is performed and recrystallization is performed.

  The invention according to claim 6 is the method for producing a highly formable Al—Mg alloy plate according to claim 5, wherein the Al—Mg alloy material plate includes Ag 0.05 to 0 in addition to the above components. An Al—Mg alloy material plate containing 6% is used.

  Furthermore, the invention of claim 7 is the method for producing a highly formable Al-Mg alloy plate according to any one of claims 1 to 5, wherein each of the Al-Mg alloy material plates is the above-described Al-Mg alloy material plate. In addition to the components, one or more of Mn 0.03-0.5%, Cr 0.03-0.3%, Zr 0.03-0.3%, and V0.03-0.3% It is characterized by using an Al-Mg based alloy material plate containing.

  According to the manufacturing method of the present invention, by applying warm different speed rolling using a lubricant under appropriate conditions, without causing the occurrence of surface defects such as cracks and adhesion of aluminum, A sound Al-Mg alloy plate having a high r value and excellent formability, particularly deep drawability, can be obtained reliably and stably in industrial production on a mass production scale. And the high formability Al-Mg type | system | group alloy board which provided the bake hard property can also be manufactured by selecting an alloy component composition appropriately.

  First, the component composition of the Al—Mg-based alloy that is the subject of this invention and the reason for its limitation will be described.

  The Al—Mg-based alloy used in the method of the present invention is basically not particularly limited as long as it contains Mg as an essential component. As an aspect of the first aspect, as defined in claim 3, there is an Al—Mg alloy containing 2.0 to 6.5% Mg and the balance being Al and inevitable impurities. Here, Mg is an additive element that contributes to the improvement of strength, elongation, and deep drawability. However, if the addition amount is less than 2.0%, the strength, elongation, and formability become insufficient, while 6.5% If it exceeds 1, the rollability is inferior, and it becomes difficult to stably perform warm different peripheral speed rolling. When such an Al—Mg alloy is used, as will be described later, as a recrystallization heat treatment after warm differential circumferential rolling, annealing is performed at a temperature within a range of 310 to 570 ° C. and recrystallization is performed. It is appropriate to form a structure, and when performing annealing as a recrystallization process in a batch furnace, it is preferable to hold at 310 to 450 ° C. for 0.5 to 24 hours, whereas when performing in a continuous annealing apparatus (CAL) For this, the condition of holding at 400 to 570 ° C. for 5 min or less is preferable.

  Furthermore, as a second aspect of the Al—Mg alloy targeted by the method of the present invention, Mg 2.0 to 6.5% and Cu 0.05 to 0.5% as defined in claim 4 are used. There is an alloy containing Al and unavoidable impurities in the balance, and as a third aspect, Mg 2.0 to 6.5% as defined in claim 5, Cu exceeding 0.5% 1 There are alloys containing 0.8% or less, the balance being Al and inevitable impurities. In any of the alloys according to claims 4 and 5, Cu, which is an element contributing to strength improvement, is added to an Al-2.0 to 6.5% Mg alloy.

  Of these, the addition of 0.05 to 0.5% Cu to the Al-2.0 to 6.5% Mg alloy as defined in claim 4 is to soften the material at the time of baking after painting and baking. Has the effect of improving the strength after baking and baking. Here, if the amount of Cu is less than 0.05%, a sufficient strength improvement effect cannot be achieved.

  When such an Al—Mg-based alloy having a Cu content of 0.05 to 0.5% as defined in claim 4 is used, the recrystallization treatment after the warm different speed rolling will be described later. In addition, annealing at a temperature within a range of 310 to 570 ° C. may be applied. In that case, batch annealing (holding at 310 to 450 ° C. for 0.5 to 24 hours) or CAL annealing (holding at 400 to 570 ° C. for 5 minutes or less) Any of) may be applied.

  On the other hand, the alloy which added more than Cu0.5% and 1.8% or less with respect to Al-2.0-6.5% Mg alloy as prescribed in claim 5 is subjected to appropriate solution treatment. By this, during baking and baking of paint after molding (during baking), the effect of precipitation hardening is higher than recovery softening and can provide bake hardness that increases the temperature compared to before baking, and the strength improvement by adding Cu The effect becomes even greater. Here, when the amount of Cu added is 0.5% or less, the bake hardness is not sufficiently imparted. On the other hand, when the amount of Cu added exceeds 1.8%, rolling cracks are likely to occur. A sound product board cannot be obtained. In order to sufficiently impart the bake hardness, the Cu content is desirably 1.0% or more.

  Here, as specified in claim 5, when adding over 0.5% Cu and 1.8% or less to provide bake hardness, the added Cu is once sufficiently dissolved in the solution. It is necessary to perform a heat treatment for rapid cooling and precipitation hardening, that is, a solution treatment, and therefore it is appropriate to perform a recrystallization treatment after warm different speed rolling in combination with a solution treatment. As a solution treatment that also serves as the recrystallization heat treatment, as explained later, the solution is heated to a temperature in the range of 510 to 580 ° C. at a heating rate of 5 ° C./sec or more and is not held or within 5 minutes. After holding, it is appropriate to cool at a cooling rate of 5 ° C./sec or less.

  Furthermore, as a fourth aspect of the Al—Mg-based alloy targeted in the present invention, 2.0 to 6.5% Mg as defined in claim 5 and Cu exceeding 0.5% and not more than 1.8% are specified. There is an alloy in which 0.05 to 0.6% of Ag is further added (alloy defined in claim 6) with respect to an alloy containing. Here, Ag is an element that contributes to strength improvement by adding together with Cu exceeding 0.5% and not more than 1.8%. If the amount of Ag added is less than 0.05%, the effect of improving the strength is poor. On the other hand, even if Ag is added in an amount of more than 0.6%, no further effect of increasing the strength can be obtained, and only the cost is increased. Therefore, the amount of Ag added is set in the range of 0.05 to 0.6%. In addition, in such an alloy in which 0.05% to 0.6% Ag is added together with Cu exceeding 0.5% and not more than 1.8%, the recrystallization heat treatment after the warm different peripheral speed rolling is performed by baking. In order to impart hardness, it is appropriate to perform the same solution treatment as described in the fifth aspect.

  Furthermore, as a 5th aspect of the Al-Mg type | system | group alloy made into object by this invention, Mn 0.03-0.5%, Cr0.03-0.3% with respect to each above Al-Mg type | mold alloy %, Zr0.03-0.3%, and V0.03-0.3% are added to one or more alloys (alloys defined in claim 7). These Mn, Cr, Zr, and V are all elements that contribute to the improvement of strength and the stabilization of recrystallized grains, and their effects are poor when added in amounts lower than their respective lower limits, while exceeding the respective upper limits. If added, coarse crystals are easily formed in the structure, which is inappropriate. The above-mentioned range of addition amounts of Mn, Cr, Zr, and V is a stipulation in the case where they are positively added to improve the strength, etc., and these alloy elements are contained as impurities in concentrations lower than their respective lower limits. In this case, it is not excluded from the target alloy of the present invention, since it has no particular influence.

  In addition, when casting a general aluminum alloy, Ti is often added as a crystal refining material, and Ti also contributes to improvement of strength and stabilization of recrystallized grains. However, it is permissible to add 0.2% or less of Ti. When Ti is added for the purpose of refining ingot crystal grains, 500 ppm or less of B or C may be added together with Ti. Furthermore, for alloys containing Mg, Be is generally added to prevent molten metal oxidation during casting. In the case of this invention as well, Be may be added as long as it is 500 ppm or less.

  In addition, examples of the inevitable impurity elements of the aluminum alloy include Fe and Si. If these elements are present in excess, ductility and formability deteriorate, so it is desirable that both be regulated to 0.25% or less.

  In the method of the present invention, it is preferable to use a hot-rolled plate as a material plate made of an Al—Mg-based alloy to be subjected to warm different peripheral speed rolling, but not limited thereto, a thin DC ingot (slab shape) Ingots) or continuous cast plates may be used.

  An Al—Mg alloy hot-rolled sheet to be subjected to warm different peripheral speed rolling can be produced by a method of hot rolling an ingot by a semi-continuous casting (DC casting) method according to a conventional method. In this case, the ingot may be chamfered according to a normal method, and it is preferable to perform a homogenization treatment at 450 to 570 ° C. for 0.5 to 24 hours before hot rolling. The hot rolling conditions are not particularly limited, but the hot rolling start temperature is preferably 350 to 500 ° C., and the hot rolled sheet has a thickness of the subsequent hot different circumferential speed rolling. Usually, it is preferable to set it as 5-120 mm, although it changes with conditions and final board product board thickness. After hot rolling, it may be cooled again to room temperature and then reheated to perform warm different peripheral speed rolling. Or you may adjust a material temperature in the range of 150-300 degreeC following hot rolling, and may perform warm different-speed rolling immediately. That is, it is normal to continue the rough hot rolling and finish rolling in the conventional general hot rolling process, and instead of the finish hot rolling, warm different peripheral speed rolling is performed. That means it ’s good.

  On the other hand, as described above, a thin DC ingot, a continuous cast plate, or the like can be used as a raw material plate as it is for warm differential rolling. Here, in the case of a thin DC ingot, a plate thickness of 50 to 120 mm is suitable, and in this case, a homogenization treatment is performed at 450 to 570 ° C. for 0.5 to 24 h before warm different peripheral speed rolling. Is preferred. When a continuous cast plate is used, twin roll type continuous casting, belt type or block type continuous casting can be used. A twin roll type continuous cast plate having a thickness of 5 to 10 mm is suitable, and a belt type or block type continuous cast plate having a thickness of 15 to 60 mm is suitable. Also in the case of these continuous cast plates, a homogenization treatment may be performed at 450 to 570 ° C. for 0.5 to 24 hours before warm different peripheral speed rolling. Furthermore, in the case of a belt-type or block-type continuous cast plate from which a thick cast plate can be obtained, it may be subjected to hot rolling anew to obtain a plate thickness of 5 to 30 mm and then subjected to warm different peripheral speed rolling.

In the method for producing an Al—Mg alloy plate according to the present invention, a hot rolled plate as described above, or a thin DC ingot or continuous cast plate is used as a material plate, and it is subjected to warm different peripheral speed rolling. In this warm different peripheral speed rolling, a lubricant is used for the purpose of preventing the occurrence of cracks and surface defects and obtaining a sound plate. Specifically, a lubricant having a kinematic viscosity at a room temperature of 25 ° C. within a range of 10 to 350 mm ² / s and a flash point of 305 ° C. or higher is suitable as the lubricant for such purpose. If the kinematic viscosity of the lubricant is less than 10 mm ² / s, the effect of preventing surface defects will be insufficient. On the other hand, if the kinematic viscosity exceeds 350 mm ² / s, it will cause a roll slip on the material and ignite during warm different speed rolling. Thus, it becomes difficult to stably apply shear deformation. Regarding the viscosity, it is desirable that the change in viscosity with temperature is small, and specifically, the viscosity temperature coefficient is desirably 0.8 or less. Further, if the flash point of the lubricating oil is less than 305 ° C., it is impossible to ignite at the time of warm different peripheral speed rolling and to perform the warm different peripheral speed rolling safely. As the lubricant satisfying the viscosity condition and the flash point as described above, a silicone-based oil is suitable, and a typical example thereof is dimethyl silicone oil.

Lubricating oil as described above is adhered to the surface of the material plate so that the amount of adhesion is in the range of 100 to 700 mg / m ² , and warm different peripheral speed rolling is performed. As the lubricating oil adhering means, it is preferable to apply directly to the surface of the material plate by spraying or the like, and an automatic application method such as electrostatic application can also be used. In some cases, it may be possible to adopt a method in which an amount of lubricating oil within a specified range adheres to the material surface by spraying on the roll surface. If the adhesion amount of lubricating oil is less than 100 mg / m ^{2, the} effect of preventing the occurrence of surface defects and adhesion of aluminum to the roll will be insufficient. On the other hand, if it exceeds 700 mg / m ² , the slip of the roll against the material will occur. The purpose of stably imparting shear deformation is not fulfilled.

  Furthermore, the material temperature at the time of warm different peripheral speed rolling shall be in the range of 150-300 degreeC. If the temperature during warm differential speed rolling is lower than 150 ° C., the deformation resistance of the material increases, so cracking is likely to occur when performing different peripheral speed rolling under high pressure, and as a result, the material is homogeneous in the material. It becomes difficult to introduce shear deformation. On the other hand, if the temperature during different peripheral speed rolling exceeds 300 ° C., recrystallization occurs during rolling, and shear deformation cannot be sufficiently introduced, so that the desired texture control becomes impossible. If the lubricating oil used in the method of the present invention exceeds 300 ° C., there is a risk of ignition and stable rolling operation cannot be performed. Depending on the component composition of the alloy and the structure of the material plate, recrystallization may occur locally even at a temperature of about 270 to 300 ° C. In this case, the recrystallization temperature of each material plate is warm. It is desirable to adjust the components so as to exceed the upper limit of the temperature at the different speed rolling, or to set the temperature of the warm different speed rolling to a temperature lower than 270 ° C.

  Furthermore, the roll peripheral speed ratio in warm different peripheral speed rolling, that is, the peripheral speed ratio on the side having a large peripheral speed with respect to the peripheral speed of the roll on the side having a small peripheral speed, is 1.2 to 2. Within the range of 5. Here, if the peripheral speed ratio is less than 1.2, it is impossible to impart sufficient shear deformation, while if it exceeds 2.5, slip between the roll and the material occurs or the material is locally localized. Deformation will occur and a normal plate cannot be obtained.

  Moreover, in the method of this invention, it is necessary to make the reduction rate in warm different peripheral speed rolling into a high pressure reduction rate exceeding 85%. That is, in the case of the method of the present invention, a lubricant is used to prevent the occurrence of surface defects and cracks at the time of warm differential circumferential rolling, and in rolling using such a lubricant, rolling is performed at a high pressure rate. Otherwise, the application of shear strain will be insufficient. In other words, even in the case of warm differential rolling at a higher rate under a higher pressure, rolling can be performed without causing cracks by using a lubricant. Here, if the rolling reduction in warm different peripheral speed rolling is less than 85%, sufficient shear deformation cannot be imparted, and improvement of the r value and deep drawability by texture control cannot be achieved. In order to further improve the moldability, the rolling reduction is preferably over 90%, and more preferably over 95%. In addition, the upper limit of the rolling reduction in the warm different peripheral speed rolling is not particularly limited, but it is usually preferably 99.5% or less in order to obtain a healthy plate material without cracks. Further, the final thickness (thickness after warm different peripheral speed rolling) is not particularly limited, but about 0.3 to 2 mm is suitable for forming.

  Of course, the rolling mill used in the warm different peripheral speed rolling needs to have a mechanism capable of driving the upper and lower rolling rolls at different peripheral speeds. The type is not particularly limited, but those in which the upper and lower rolls are separately driven by a variable speed motor or those in which the ratio of the peripheral speed can be changed by a mechanical mechanism such as a gear are suitable. In order to stably perform the warm different peripheral speed rolling, it is desirable to use a rolling mill having a roll heating mechanism. In this case, either a heater may be included in the roll, or a heater for heating the roll may be installed outside the roll.

  The Al-Mg alloy sheet having a predetermined thickness obtained by performing the warm different peripheral speed rolling as described above is then recrystallized by performing recrystallization heat treatment (in combination with annealing or solution treatment). Thus, a texture state with a high r value and good deep drawability can be obtained. That is, in order to obtain the ultimate high formability, particularly excellent deep drawability, in the present invention, the plane of the crystal orientation {111} and the plane close to it in the plate surface having the effect of increasing the average r value. It is necessary that the orientation accumulation density is high. Specifically, one or more of crystal orientations in which {111}, {332} and {221} are parallel to the plate surface are random as the orientation accumulation density. It is preferably 1.2 times or more, more preferably 1.5 times or more, and in addition to this, the density of {100} orientation planes that tend to lower the average r value is low. However, it is desirable that the orientation density of the {100} orientation is 0.9 times or less of the random, and in order to stably obtain such a crystal structure, It is necessary to recrystallize. Note that the orientation density of the crystal structure may be obtained by any analysis method such as an X-ray diffraction method or an EBSP method. However, at the time of this analysis, in order to confirm that the material as a whole is in an appropriate textured state, it is necessary to confirm that the above-mentioned criteria are satisfied on average over the entire plate thickness.

  The recrystallization heat treatment as described above is carried out as annealing for the purpose of recovery / recrystallization only, depending on the component composition of the target Al—Mg alloy, and elements contributing to precipitation hardening such as Cu and Ag. In some cases, it is also performed as a solution treatment for solid solution. That is, first, an Mg—2.0 to 6.5% Mg as defined in claim 3 and an Al—Mg-based alloy consisting of the balance Al and unavoidable impurities, and Mg 2.0 to In the case of an Al—Mg alloy composed of 6.5%, Cu 0.05 to 0.5%, the balance Al and inevitable impurities, the recrystallization heat treatment is performed mainly for recovery and recrystallization. In this case, the heating temperature for annealing is set within a range of 310 to 570 ° C. If the annealing temperature is lower than 310 ° C., the recrystallization is insufficient and unsuitable, and if it exceeds 570 ° C., melting occurs locally, and therefore inappropriate. Moreover, when performing this annealing with a batch furnace, the conditions of holding at 310-450 degreeC for 0.5-24h are preferable. On the other hand, when this annealing is performed with a continuous annealing apparatus (CAL), the condition of no holding at 400 to 570 ° C. or holding for 5 min or less is preferable. Note that annealing by CAL is characterized by a heating rate of heating of 5 ° C./sec or more, rapid heating and rapid cooling by a cooling rate, and it is performed in the laboratory instead of annealing by a salt bath. be able to.

  On the other hand, as defined in claim 5, in addition to 2.0 to 6.5% Mg, when more than 0.5% and 1.8% or less of Cu is added, or as defined in claim 6. When adding more than 0.5% Cu and less than 1.8% Cu and 0.05 to 0.5% Ag, that is, when bake hardness is imparted, After sufficiently adding the added Cu or the like to the solid solution, it is necessary to rapidly cool from that state and perform a heat treatment for providing precipitation hardening ability, that is, a solution treatment. The heating temperature in the solution treatment is a temperature within a range of 510 to 570 ° C, preferably a temperature within a range of 535 to 570 ° C. The solution treatment can be performed by CAL. The holding time is 0 min (that is, cooling immediately after reaching the temperature) to 5 min, and the heating is performed by rapid heating and rapid cooling at 5 ° C./sec or more. Such rapid heating and rapid cooling can also be performed by salt bath heating and water quenching or forced air cooling.

  Examples of the present invention are shown below together with comparative examples.

  Alloys having respective component compositions shown in alloy codes A to Q of Table 1 were melted in accordance with a conventional method to obtain a DC ingot having a cross section having a thickness of 80 mm and a width of 200 mm. In addition, in the ingot of the alloy composition of P and Q exceeding the upper limit of the amount of Mn, Cr, Zr and V specified in claim 7, it was confirmed that a coarse intermetallic compound was formed in the structure. Therefore, it was judged to be inappropriate, and it was excluded from the subsequent processes and test subjects. In addition, the DC ingots of the alloys A to O were subjected to homogenization treatment at 500 ° C. × 10 h, and then subjected to preparatory processing so as to be a base material (material plate) for warm different peripheral speed rolling. That is, when a hot-rolled sheet is used as a base material (in the case of rolling conditions R1 to R4 and R7 to R18 in Table 2 showing rolling conditions of different peripheral speed rolling), both surfaces are chamfered to a thickness of 72 mm. After preheating at 430 ° C. for 2 hours, hot rolling was performed to the rolling start plate thickness described in Table 2 (indicating the plate thickness at the start of different peripheral speed rolling). On the other hand, when the DC ingot was used as a base material as it was (rolling condition R5 in Table 2), the ingot was chamfered to a thickness of 72 mm and used as the base plate. In addition, in rolling condition R6 of Table 2, a continuous cast plate having a thickness of 7.2 mm produced by a twin roll method was used as a base plate, and this was previously subjected to a homogenization treatment at 460 ° C. for 10 hours. .

  The base plate made of each alloy as described above was subjected to warm different peripheral speed rolling under the conditions indicated by R1 to R18 in Table 2. In addition, before the warm different peripheral speed rolling, preheating was performed to hold each base material at a predetermined rolling temperature for 2 hours. The used rolling mill includes a heater in the roll, and at the time of warm different peripheral speed rolling, the temperature of the roll is set within a range of −15 ° C. to + 0 ° C. with respect to a predetermined rolling temperature by this heater. Control was performed. In this rolling, the peripheral speed of one roll was fixed at 20 m / min, and the peripheral speed of the other roll was changed to obtain a predetermined peripheral speed ratio. Several types of silicone oil (dimethyl silicone oil) were used as rolling lubricants, but all of these flash points were in the range of 310 ° C. to 320 ° C., and kinematic viscosities at room temperature are shown in Table 2, respectively. Furthermore, the viscosity temperature coefficient is in the range of 0.55 to 0.65. The lubricating oil was applied in the amount shown in Table 2 on the surface of the original material immediately before warm rolling by an electrostatic coating apparatus, and the amount of wear was appropriately supplemented between rolling passes. After warm different peripheral speed rolling, recrystallization heat treatment was performed. As the recrystallization heat treatment, as shown in the heat treatment conditions HT1 to HT5 in Table 3, the recrystallization heat treatment was performed by either batch annealing or salt bath annealing (solution treatment) corresponding to CAL continuous annealing.

  About each rolled sheet obtained by carrying out warm different peripheral speed rolling as mentioned above, while examining the soundness, as mechanical properties, tensile strength, proof stress, elongation, and also as bake hard (BH) property evaluation Since the yield strength after stretching and the yield strength after baking hard (BH) were examined, the results are shown in Tables 4 and 5. These evaluation methods and test methods are as follows.

  The soundness of the rolled sheet was evaluated by appearance and cross-sectional observation. That is, it was set as XX when cracking, shape defect, swelling, etc. were caused by rolling or subsequent heat treatment and subsequent characteristic evaluation was impossible. In addition, when a cross section having a length of 100 mm parallel to the rolling direction of the material was observed at five locations, a surface crack defect having a depth of 30 μm or more (3% or more with respect to the plate thickness) was indicated as x, which was recognized. If not, it was judged as good and marked as o. For mechanical properties, JIS No. 5 test pieces were cut in the rolling direction (0 °), and tensile strength, proof stress and elongation were evaluated by a tensile test. In the evaluation of the bake hard (BH) property, the tensile test piece was subjected to a 2% tensile deformation (stretch) corresponding to the processing strain in normal molding, and then subjected to a BH treatment for 20 minutes at 170 ° C. The yield strength after BH treatment and the yield strength after BH treatment were determined.

  Furthermore, for each rolled plate obtained as described above, the orientation density of each crystal plane affecting the r value of the material after recrystallization heat treatment was examined, and the average r value and deep drawability were examined. The results are shown in Tables 6 and 7. Each measuring method and evaluation method are as follows.

  The orientation density of each crystal plane was measured by SEM-EBSP. In EBSP, the crystal orientation at each measurement point and the crystal plane parallel to the rolled plate surface are analyzed in the cross section in the rolling direction, and the integration density (magnification relative to random) can be calculated from information on all measurement points. By this method, the texture state in the entire plate thickness can be captured. Specifically, EBSP measurement was performed at an analysis interval of 2.5 μm for 10 observation regions of plate thickness (1000 μm) × length (400 μm), and these were averaged to obtain a plane orientation of {111}, {332}, The orientation density of {221} and {100} was determined. The average r value was calculated from each direction r value at 15% strain by pulling a JIS No. 5 test piece in the direction of 0 °, 45 ° and 95 ° with respect to the rolling direction by a tensile test. Further, the deep drawability was evaluated by measuring the limit drawing ratio (LDR).

  As shown in Table 4, all of Examples 1 to 21 of the present invention are applied with a lubricant under appropriate conditions and are subjected to warm different peripheral speed rolling, and are predetermined without causing problematic cracks and defective shapes. It was possible to roll up to a plate thickness, and no problem of surface defects of the plate occurred. Moreover, in these invention examples 1-21, as shown in Table 6, {111}, {332}, which are effective in improving the average r value by warm different peripheral speed rolling and recrystallization heat treatment under appropriate conditions The orientation integration density of any of the {221} plane orientations is 1.5 times or more random, and the orientation integration density of the {100} plane that tends to lower the average r value is 0.9 times or less. It was. As a result, it was found that the average r value was 0.9 or more and the deep drawability represented by LDR was good. Among these, when the rolling reduction ratio of the warm different peripheral speed rolling exceeds 95%, an average r value of 1.0 or more was stably obtained, and a more desirable state was obtained (in Alloy E, Invention Examples 7 to 7). 10). It should be noted that even if the accumulation of {111} orientations, which is effective for the high r value said in the literature, is relatively weak, the accumulation of orientations {332}, {221}, etc. close to it is high, {100 } It has been confirmed that a high r value is achieved if the integration of the surface is low (for example, Invention Example 14).

  Here, of Invention Examples 1 to 21, Invention Examples 1 to 3 and 20 to 21 are cases where Cu is not added as a material alloy or the amount of Cu addition is as small as 0.5% or less. Then, it does not have BH property (strength after stretching = strength before BH is higher than after BH treatment). On the other hand, Invention Examples 4 to 19 are examples in which an Al—Mg-based alloy having bake hardness added with Cu exceeding 0.5% is used as a raw material, and among these, Invention Example 7 (E alloy, Cu 1.07) %), The strength after BH treatment is higher than that of Invention Example 4 (D alloy, Cu 0.68%). Therefore, when better BH properties are required, a Cu addition amount exceeding 1% is desirable. Is clear. In particular, Invention Examples 16 to 18 to which Ag was added exhibited high BH properties, and were able to achieve both a high r value and high moldability.

  On the other hand, as shown in Tables 5 and 7, in the case of Comparative Examples 1 to 18, any of the performances was inferior to the inventive examples.

  That is, Comparative Example 1 is an example in which the amount of Mg added is small. In this case, the strength is low even if the other conditions are within the scope of the present invention, so that it is not suitable as a molding plate for an automotive outer plate. became. Furthermore, Comparative Example 2 is an example in which the amount of Mg in the alloy is too high, and remarkable cracking occurred during rolling with different peripheral speeds, making rolling impossible. Furthermore, Comparative Example 3 is an example in which the amount of Cu added is too large. In this case, too, cracks occurred during the rolling with different speeds at the warm temperature, making rolling impossible.

  On the other hand, Comparative Example 4 is an example in which cold rolling at equal circumferential speed is applied to an alloy within the composition range of the present invention. In this case, the {111}, {332}, {221} plane orientation azimuth density effective for improving the average r value is low, while the {100} plane azimuth density is effective in reducing the average r value. Therefore, the average r value was as low as 0.7 or less, and the LDR was also lower than that of the inventive examples. Further, Comparative Example 5 is an example in which uniform circumferential speed rolling was performed in this case. In this case as well, the orientation density was inappropriate, and as a result, the average r value was low and the LDR was also lower than that of the inventive example.

  Further, Comparative Example 6 is an example in which the rolling reduction ratio of the warm different peripheral speed rolling is low. In this case, the {100} plane orientation density is high, and as a result, the average r value and LDR are lower than those of the inventive examples. Comparative Example 7 is an example in which the peripheral speed ratio of warm different peripheral speed rolling is low. In this case as well, the {100} plane orientation accumulation density was high, and the average r value and LDR were lower than those of the inventive examples. Further, Comparative Example 8 is an example in which the peripheral speed ratio of warm different peripheral speed rolling is high. In this case, the material is greatly warped during rolling, and uniform and stable rolling cannot be performed, and locally large cracks occur. Occurred and rolling could not be completed. Moreover, although the comparative example 9 is an example where the temperature of warm different peripheral speed rolling is low, the rolling could not be completed due to cracking.

  Further, Comparative Example 10 is an example in which the kinematic viscosity of the lubricating oil of the warm different peripheral speed rolling is low, the adhesion to the roll could not be sufficiently suppressed, and as a result, a minute crack defect was generated on the plate surface. On the other hand, Comparative Example 11 is an example in which the kinematic viscosity of the lubricating oil of warm different peripheral speed rolling is high. In this case, roll slip occurred during rolling, and the deformation of the material became uneven, and the rolling could not be completed.

  Further, Comparative Example 12 is an example in which warm different peripheral speed rolling was performed without lubrication. Although it was possible to roll the B alloy (Al-3.02% Mg) to a predetermined plate thickness at a reduction rate of 87.8%, surface defects were generated and the ductility was lower than the invention example of the alloy. It was. Further, Comparative Example 13 is also an example in which warm different peripheral speed rolling was performed without lubrication. In this example, a J alloy having a larger alloy addition amount than that in Comparative Example 12 is used, and in this case, due to rolling cracks. Rolling with a reduction ratio of 87.8% could not be completed. Further, Comparative Example 14 also tried warm different peripheral speed rolling with a rolling reduction of 96.3% under non-lubricating conditions, but rolling could not be continued to a predetermined plate thickness due to occurrence of rolling cracks.

  On the other hand, Comparative Example 15 is an example in which the amount of the lubricating oil applied in the warm different peripheral speed rolling is small, and in this case, surface defects (surface cracks) could not be prevented. Further, Comparative Example 16 is an example in which the amount of lubricating oil applied in warm different peripheral speed rolling is large, but in this case, slip occurs between the roll and the material during rolling, so that the deformation of the material becomes uneven, The rolling could not be completed due to significant material bending.

  Comparative Example 17 is an example in which the temperature of the recrystallization heat treatment (solution treatment) was too high at 580 ° C. In this case, local melting occurred during the treatment, and thus surface swelling occurred. On the other hand, Comparative Example 18 is an example at a temperature of 470 ° C. where the solution treatment temperature is low, and the yield strength after the BH treatment is lower than that of the similar E alloy invention example. In addition, when this processing temperature is 280 degreeC, it is confirmed separately that it becomes a structure | tissue in which an unrecrystallized part remains.

Claims (7)

  About Al-Mg type alloy material plate, with a lubricant applied to the surface, at a temperature in the range of 150 to 300 ° C, the roll peripheral speed ratio is in the range of 1.2 to 2.5 and 85%. A high formability Al, characterized in that a warm different peripheral speed rolling is performed under conditions of a rolling reduction exceeding, and then a recrystallization heat treatment is performed to obtain an Al-Mg based alloy sheet having an average r value of 0.9 or more. -Manufacturing method of Mg type alloy plate. In the manufacturing method of the high formability Al-Mg alloy plate according to claim 1,
As the lubricant, a lubricating oil having a kinematic viscosity at normal temperature of 10 to 350 mm ² / s and a flash point of 305 ° C. or higher is used, and the amount of the lubricating oil adhered is in the range of 100 to 700 mg / m ^2. A method for producing a highly formable Al—Mg alloy plate, characterized in that it is attached to an Al—Mg alloy material plate and subjected to warm differential circumferential rolling. In the manufacturing method of the highly formable Al-Mg type alloy plate according to claim 1 or 2,
As the Al—Mg-based alloy material plate, an Al—Mg-based alloy plate containing Mg 2.0 to 6.5% (mass%, the same shall apply hereinafter), the balance being Al and inevitable impurities is used on the surface thereof. A high formability Al, characterized in that after performing warm different speed rolling in a state where a lubricant is applied, the recrystallization heat treatment is performed by annealing at a temperature within a range of 310 to 570 ° C. and recrystallization. -Manufacturing method of Mg type alloy plate. In the manufacturing method of the highly formable Al-Mg type alloy plate according to claim 1 or 2,
As the Al—Mg-based alloy material plate, an Al—Mg-based alloy plate containing Mg 2.0 to 6.5% and Cu 0.05 to 0.5%, the balance consisting of Al and inevitable impurities is used. High-forming, characterized in that after carrying out warm different speed rolling in a state where a lubricant is applied to the surface, the recrystallization heat treatment is annealed and recrystallized at a temperature within a range of 310 to 570 ° C. For producing a conductive Al-Mg alloy plate. In the manufacturing method of the highly formable Al-Mg type alloy plate according to claim 1 or 2,
As the Al—Mg-based alloy material plate, an Al—Mg-based alloy plate containing Mg 2.0 to 6.5% and Cu exceeding 0.5% and 1.8% or less, with the balance being Al and inevitable impurities. Use, after carrying out the warm different peripheral speed rolling in the state which provided the lubricant to the surface, as a recrystallization heat treatment, it carries out the solution treatment which heats to the temperature of 510-570 ° C, and is recrystallized A method for producing a highly formable Al—Mg alloy plate. In the manufacturing method of the high formability Al-Mg alloy plate according to claim 5,
The Al-Mg-based alloy material plate is an Al-Mg-based alloy material plate containing 0.05% to 0.6% Ag in addition to the above components. Manufacturing method of alloy plate. In the manufacturing method of the high formability Al-Mg alloy plate according to any one of claims 1 to 5,
As the Al—Mg alloy material plate, in addition to the above components, Mn 0.03 to 0.5%, Cr 0.03 to 0.3%, Zr 0.03 to 0.3%, and V 0.03 to 0 A method for producing a highly formable Al—Mg alloy plate, comprising using an Al—Mg alloy material plate containing one or more of 3%.